Method of making ball pens



June 1968 mzuo ISHIZUKA $339,456

METHOD OF MAKING BALL PENS Filed June 16, 1966 2 Sheets-Sheet 1 June 1968 KAZUO ISHIZUKA 3,339,456

METHOD OF MAKING BALL PENS Filed June 16, 1966 2 Sheets-Sheet 2 United States Patent 0 METHOD OF MAKING BALL PENS Kazuo Ishizuka, Tokyo, Japan, assignor to Mitsu-bishi Pencil Company Limited, Tokyo, Japan Filed June 16, 1966, Ser. No. 557,936 Ciaims priority, application Japan, Oct. 2, 1965, 40/59,9S4 2 Claims. (Cl. 29-441) This invention relates to methods of making ball pens.

It is necessary that the material for ball pen tips should be provided with a ductility, machinability and wearresistance. That is to say, the ductility is necessary for calking the ball holding part. The machinability is indispensable for forming the contour and making the ink leading hole. The wear-resistance is important to prevent the ball receiving seat part from being easily worn by the rolling of the ball in the use and to increase the life of the ball pen tip.

For this purpose, exclusively brass has been so far used. However, brass is not good enough to secure the wear-resistance and to improve the Writing quality by reducing the friction of the ball.

Further, there are tips formed of a synthetic resin to be used as a wear-resistant material for bearings. However, as such synthetic resin has no ductility, it is necessary to calk the resin by heating and softening it. Therefore, there is a defect that, in calking the resin, the ball fitting hole will be deformed so much that the ball will not roll smoothly.

In the present invention, there is no such defect, ball pen tips can be easily made by using the conventional ball pen tip manufacturing apparatus, the wear-resistance and writing quality are improved by using a synthetic resin for the ball receiving seat and the synthetic resin can be securely and positively fixed to the metallic base part.

An object of the present invention is to provide a ball pen which is high in the writing quality and is long in the life and in which the combination of the tip with the ink tube is perfect.

Another object of the present invention is to provide a method of making ball pens in which a proper synthetic resin or metal is used for the ball receiving seat so that the wear-resistance may be high.

A further object of the present invention is to provide a method of making ball pens in which the combination of the tip with the ink tube is perfect.

In the accompanying drawings,

FIGS. 1A to 1B are sectional views of a ball pen tip in respective steps of the method of the present invention;

FIG. 2 is a sectional view showing another embodiment and corresponding to FIG. 1B.

First of all, as in FIG. 1A, an axial through hole 2 of any desired form is made in a round-sectioned bar 1 of such metal high in the machinability and ductility as, for example, brass and a female screw 3 is formed at one end of the hole 2. Such hole is filled With such wear-resistant synthetic resin as Delrin or nylon by such method as injection molding or pouring so as to be integrally formed. FIG. 1B shows such state. The brass bar 1 is filled in the axis part with a ball receiving seat material 4 of a synthetic resin for bearings low in the friction. This material bar 1 is fed, for example, to a conventional automatic ball pen tip manufacturing apparatus, is first cut at the forward end 5 and in any other proper part so as to form the contour, is then drilled in the axis part from the end part in which is formed the female screw 3 so as to form an ink hole 6 as in FIG. 1C and is further drilled from the forward end side of the tip so as to form a ball fitting hole 7. An ink hole 8 communicating with hole 6 is then made.

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Several ink leading grooves 9 are formed by broaching in the bottom part of the hole 7. FIG. 1D shows such state.

Said ball fitting hole 7 can be easily precisely machined by blowing low temperature air cooled, for example, with Dry Ice through a nozzle onto the forward end of the tip. A ball 10 is fitted in the above described hole 7 at the forward end of the tip and the hole 7 is roll-calked on the peripheral edge 11 so as to be contracted a little inward to prevent the ball from coming out. Thus the tip is finished. In the above mentioned embodiment, the diameter a of the ball fitting hole 7 is made equal to or a little larger than the diameter b of the receiving seat material 4 in that part. But, by making the diameter c of the hole 7 somewhat smaller than the diameter d of the receiving seat material 4 as shown in FIG. 2, the synthetic resin canbe arranged not only on the receiving seat 12 for the ball 10 but also on the side of the ball.

Thus, in the present invention, the hole 2 having the female screw 3 is made in the axis part of the metallic bar high in the machinability and ductility and is filled with the receiving seat material of such synthetic resin having a Wear-resistance and low in the friction as Delrin or nylon so as to be integrally formed, then the ball fitting hole 7, ink holes 6 and 8 and leading grooves 9 are made, the ball 10 is fitted in the hole 7 and the hole edge 11 is calked. That is to say, as the receiving seat 12 for the ball 10 is formed of the material having a wear-resistance and low in the friction and therefore the thus produced tip is longer in the life and is higher in the writing quality than any conventional tip made of brass.

Further, as all the ink leading holes are in the synthetic resin and ink does not come into contact with any metallic part, there is no fear that rust will be produced by the chemical action of the ink and metal.

As the edge 11 of the ball fitting hole is formed of the metal high in the ductility, it is not necessary as in a tip made of a synthetic resin to heat and soften it in working it. Only the required part can be cold-calked to be locally transformed so as to hold the ball. Therefore, a good tip can be made definitely at a high precision without a fear that the inside of the hole 7 will be deformed and that the smooth rolling of the ball will be obstructed. As the hole 2 is provided with the female screw 3 and is filled with the receiving seat material 4 of the synthetic resin, in the case of making the ink hole 6 With a drill, if the receiving seat material 4 rotates with the rotation of the drill, it Will be fed in the direction of being fastened by the above mentioned female screw. Therefore, the receiving seat material 4 and the metallic bar 1 will be very securely fixed together to be perfectly integrally formed. Therefore, there is no difficulty that, while the ball fitting hole 7 is being worked or during the use of the ball pen, looseness or slight movement will be produced between the receiving seat and the bar 1 or the metallic base part and the smooth rolling of the ball will be obstructed. Further, there is no fear that, in the case of the low temperature working by blowing low temperature air as described above, looseness Will be produced or the receiving seat material will be dropped off by the contraction or expansion due to the temperature variation. The respective manufacturing steps can be carried out substantially as eiliciently and quickly as the conventional ball pen tip manufacturing steps and are adapted to mass production.

What is claimed is:

1. A method of making ball pens comprising steps of making a hole in the axis part of a round-sectioned metallic bar having high ductility and machinability, forming a female screw at least in a part of said hole, filling said hole with a receiving seat material having a wear-resist- 3 4 ance and low in the friction so as to integrally form a tip References Cited member, making an ink hole and a ball fitting hole in UNITED STATES PATENTS said tip member by machining, fitting a ball in said fitting hole formed of the metal having high ductility in the peripheral edge part and of the receiving seat material 5 in the bottom part and contracting said ball fitting hole on the peripheral edge.

2. The method of making ball pens according to claim 1 wherein said ball fitting hole is formed of the receiving seat material. 10

2,646,761 7/ 1953 Knobel.

2,983,253 5/1961 Henriksen 120-42.4 3,099,082 7/1963 Henriksen.

3,181,228 5/1965 Droubay.

THOMAS H. EAGER, Primary Examiner. 

1. A METHOD OF MAKING BALL PENS COMPRISING STEPS OF MAKING A HOLE IN THE AXIS PART OF A ROUND-SECTIONED METALLIC BAR HAVING HIGH DUCTILITY AND MACHINABILITY, FORMING A FEMALE SCREW AT LEAST IN A PART OF SAID HOLE, FILLING SAID HOLE WITH A RECEIVING SEAT MATERIAL HAVING A WEAR-RESISTANCE AND LOW IN THE FRICTION SO AS TO INTEGRALLY FORM A TIP MEMBER, MAKING AN INK HOLE AND A BALL FITTING HOLE IN SAID TIP MEMBER BY MACHINING, FITTING A BALL IN SAID FITTING HOLE FORMED OF THE METAL HAVING HIGH DUCTILITY IN THE PERIPHERAL EDGE PART AND OF THE RECEIVING SEAT MATERIAL IN THE BOTTOM PART AND CONTRACTING SAID BALL FITTING HOLE ON THE PERIPHERAL EDGE. 